1. Field of the Invention
The present invention relates to CRT (Cathode Ray Tube) devices used for TVs and computer displays, and deflection yokes used in such CRT devices, particularly to the structures of the deflection yokes.
2. Description of the Related Art
FIG. 1 is a cross section of a ferrite core, generally called a slot core, being sectioned at a plane perpendicular to the Z axis (the tube axis). The ferrite core 100 in the deflection yoke has, on the inner wall thereof, a plurality of ridges 102 each of which protrudes substantially toward the Z axis (positioned at the center 0) and extends along the Z axis direction, the plurality of ridges 102 being arranged circumferentially. A vertical deflection coil 106 and a horizontal deflection coil 108 are wound so as to be in each slot 104 formed between the ridges 102 positioned adjacent to each other, with an insulating spacer 110 interposed between the deflection coils. The cross sections of the deflection coils are simply indicated with hatching. This technique is disclosed in the Japanese Unexamined Utility Model Application Publication No. 61-56757. The envelope formed by the bottoms of the slots 104 is circular. The envelope formed by the tips of the ridges 102 is also circular. These envelopes are concentric circles having the Z axis as the center.
A deflection yoke with such arrangements has the following advantageous effects over a deflection yoke including a ferrite core that has a smooth inner wall without ridges and slots: The deflection sensitivity is improved because it is possible to position the ferrite core closer to the cathode ray tube, through which the electron beams pass. Also, it is possible to reduce eddy-current loss and inhibit heat generation of the deflection yoke because the magnetic flux is less likely to have a flux linkage with the deflection coils. Consequently, it is possible to save electric energy at the deflection yoke.
In recent years, energy-saving techniques have been an issue in various fields in view of the problems of environmental destruction. The field of CRT (Cathode Ray Tube) devices is not an exception. There are demands for further reduction in electric power consumption even with slot-core type deflection yokes that are already characterized with their lower electric power consumption.